I don't care if she apologized, she still stole your commission. She knew what she was doing. Keep your "nasty-pants" coolly polite explaining voice ready for this one and others like her. I worked as a secretary in a real estate office and believe me learned a thing or two watching the ladies do their jobs. Everyone was nice but you knew not to mess with them.

If nothing else, the commission should be divided (set up meeting with manage) since your set this sale up (referrel or something)